Active object falls only through parts of the other active object
I think you may have edited the object after applying the RB, delete the the current RB sim and reapply with collision type as mesh.

edit:i think I know the problem your object does not move, normally rbs are added to moving objects by default, yours doesn't, causing some problems, i tried recreating the scene and ended up with messing in the sensitivity panel and the dynamics parts, what you want to do is try adding a small amount of sensitivity, and disable the dynamics in it, reply if this worked.